1. Field of Art
This invention relates to the improvement of an agricultural harvesting machine. More specifically it relates to an improvement to the drive shaft on a pull-type forage harvester.
2. Description of Prior Art
Pull type forage harvesters have been used in farming operations for decades. The forage harvester is designed to cut and process crops so that livestock can consume the crop material. The pull-type forage harvester is towed and powered by a conventional agricultural tractor. As the harvester is pulled across a field, it receives crop into its header. The crop is then passed into the cutterhead. The cutterhead chops the crop material into lengths that are desirable to various farm animals. In some machines the crop material is further passed through a corn processor that crushes and opens corn kernels. The crop material is next dropped in an auger trough. The auger in the trough pushes the crop material to a blower. The blower forces the crop material through the blower chute. The chute directs the crop material into an appropriate container for transport. As previously mentioned, the harvester is pulled by a tractor by means of a pivot tongue. Rotational power is transmitted from the power-take-off (PTO) of the tractor to a gearbox on the forage harvester by means of a drive shaft or drive line positioned proximate to the pivot tongue. As the complexity of the forage harvesters has grown, new problems associated with the transmission of the power have also grown. Previously, some drivelines were only 6 feet in length. With newer machines, it is common for the driveline to extend at least 10 feet. However, drivelines are difficult to manufacture. Increasing the length of a driveline results in more expensive manufacturing methods and machinery. A means to couple several of the drive lines together without loss of the rotational energy and with a minimum of support structure would be a great improvement.
The prior art illustrates these and other difficulties. U.S. Pat. No. 2,255,634 illustrates a flange union that couples two shafts. Unfortunately, it is necessary to clamp the flange tightly. Considerable stress is placed on the clamping bolts. U.S. Pat. No. 4,598,677 illustrates an arrangement of auxiliary equipment units for internal combustion engine automotive vehicles. In this design it is necessary for the coupler to be held in position by a seal and a set of bearings. This increases the costs and risk of coupler failure.
Consequently, the need exists for improved mechanisms for joining the various drive shafts with a minimum of supports that ensures that the rotation power from the PTO is transmitted to the harvester.
It is an object of the present invention to provide a shaft coupler for the drive shaft of a forage harvester.
It is a further object of the present invention to provide a coupler that is not supported by any structure besides the drive shaft.
It is a further object of the present invention to provide a shaft coupler that is simple and inexpensive to build and maintain.
It is a further object of the present invention to provide a shaft coupler that transmits the rotational power of the tractor PTO to forage harvester without loss.
It is a further object of the present invention to provide a method of constructing and assembling a shaft coupler.
The invention overcomes the deficiencies of the prior art. The invention is an improvement to the driveline on a pull type forage harvester. The invention consists of a set of first tapered splines on a first drive shaft and a set of second tapered splines on a second drive shaft. The first and second tapered splines are inserted into an internally splined, tapered coupler with a gap at the center. To maintain the splines in mated contact; a retainer is affixed onto each drive shaft by means of a first retaining ring. Retaining bolts may be used to draw the shafts into the coupler. A method for constructing the invention consists of cutting a groove into each drive shaft for a retaining ring. A tapered hobbing tool is used to cut splines into the drive shaft. A boring bar is used in conjunction with a lathe to cut a tapered bore into the coupler. A broaching tool is used to cut the internal splines for the coupler.